BACKGROUND
[0001] For cardiac arrest victims, cardiopulmonary resuscitation (CPR) may include a variety
of therapeutic interventions including chest compressions, defibrillation, and ventilation.
Chest compressions during CPR may maintain blood circulation so that oxygen can be
delivered to the body until the heart resumes an effective rhythm. The chest compressions
may be performed by automated mechanical devices, such as, for example, the ZOLL®
AutoPulse®. Alternatively, or additionally, the chest compressions may be performed
manually, for example, by compressing the chest of a victim with the hands of a rescuer,
or manually with mechanical assistance, for example, by compressing the chest of the
victim with a hand-held device such as, for example, the ZOLL® ResQPump®. Feedback
relating to characteristics of the chest compressions may be provided to the rescuer
in real-time during the chest compressions. Such feedback may allow the rescuer to
modify and, thereby, improve the efficacy of the chest compressions. The feedback
may also allow the rescuer to more effectively combine and coordinate the chest compressions
with other resuscitative therapies.
US 8942803 describes systems and methods for use during the administration of CPR chest compressions
and defibrillating shocks on a cardiac arrest victim, such as analyzing compression
waveforms from a compression depth monitor to determine the source of chest compressions,
and enabling the delivery of defibrillating shock during a compression cycle if the
compression waveforms are characteristic of an automated CPR chest compression device.
SUMMARY
[0002] According to the invention, a system for assisting a rescuer in providing resuscitative
treatment in accordance with claim 1 is provided.
[0003] Implementations of such a system may include one or more of the following features.
The predetermined criterion may be a chest compression rate specification for the
automated chest compression device. The predetermined criterion may be a threshold
variability of a chest compression rate. The processor may be configured to compare
a measured variability of the chest compression rate with the threshold variability
of the chest compression rate, determine that the chest compressions are the automated
chest compressions if the measured variability of the chest compression rate is below
the threshold variability, and determine that the chest compressions are the manually
delivered chest compressions if the measured variability of the chest compression
rate is above the threshold variability. The processor may be configured to compare
the detected features to an additional criterion that determines whether the chest
compressions are active compression decompression (ACD) chest compressions provided
by an ACD chest compression delivery system that includes one of a hand-held ACD chest
compression device and an ACD system configured to provide automated ACD chest compressions.
The detected features may include a shape of at least a portion of the compression
waveform. The additional criterion may include the shape exhibiting one or more of
a shoulder feature preceding a peak in a velocity waveform, the shoulder feature being
characterized by at least two changes in slope of the compression waveform and waveform
shape features indicative of one or more mechanical components of the ACD chest compression
delivery system. The chest compressions may be delivered via the hand-held ACD chest
compression device. The processor may be configured to dynamically determine a compression
neutral point, provide chest compression rate feedback, and provide chest compression
depth feedback and the chest compression depth feedback may include a compression
non-elevated depth and a decompression elevated height. The chest compressions may
be delivered via the hand-held ACD chest compression device and the processor may
be configured to control the at least one output device to provide chest compression
rate feedback and withhold chest compression depth feedback. The at least one motion
sensor may include an accelerometer. The compression waveform may include one or more
of an acceleration waveform, a velocity waveform, and a displacement waveform. The
features may include one or more of a compression rate, a compression depth, a hold
time, a velocity minimum-to-maximum time, a velocity amplitude, a compression width,
a release time, a relaxation time, a variability of at least one compression parameter,
and a shape of at least a portion of the compression waveform. The chest compression
feedback may include one or more of visible feedback, audible feedback, haptic feedback,
numerical feedback, and graphical feedback. The processor may be configured to control
the at least one output device to provide to the rescuer one or more of instructions,
alarms, treatment event reminders, and treatment event timing information. The instructions
may include one or more of a prompt to start resuscitative treatment, a prompt to
determine if the victim requires CPR, a prompt to start the manually delivered chest
compressions, a prompt to determine if the rescuer wants to provide the automated
chest compressions, a prompt to attach the automated chest compression device to the
victim, and a prompt to determine if the rescuer wants to continue CPR. The system
may further include a defibrillator communicatively coupled to the processor and configured
to provide a defibrillation shock and may include defibrillation electrodes configured
to couple to the defibrillator and the victim and to deliver the defibrillation shock
to the victim. The processor may be configured to control the delivery of the defibrillation
shock based at least in part on the detected features in the compression waveform.
The defibrillator may be configured to analyze an electrocardiogram (ECG) of the victim.
The processor may be configured to control the delivery of the defibrillation shock
based on the ECG. The processor may be configured to stop the automated chest compressions
prior to the analysis of the ECG of the victim. The processor may be configured to
control the at least one output device to provide one or more of an instruction to
the rescuer to use the defibrillator to deliver the defibrillation shock to the victim,
and defibrillation parameter feedback for the rescuer. The defibrillation parameter
feedback may include one or more of shock energy information, electrocardiogram information,
defibrillator equipment status, defibrillator data analysis status, shock timing information,
pacer information, and chest impedance information. The system may include a communications
interface coupled to the processor. The processor may be configured to store resuscitative
treatment information in the memory and to transmit the resuscitative treatment information
via the communications interface. The stored resuscitative treatment information may
include an indication of whether the chest compressions are the manually delivered
chest compressions or the automated chest compressions. The automated chest compression
device may be a belt-based compression device or a piston-based compression device.
The system may include one or more physiological sensors communicatively coupled to
the processor and configured to generate signals indicative of physiological parameter
information for the victim. The processor may be configured to determine the physiological
parameter information and to control the at least one output device to provide the
physiological parameter information to the rescuer. The chest compression feedback
may be based on the physiological parameter information. The physiological parameter
information may include one or more of blood pressure information, electrocardiogram
(ECG) information, blood flow information, chest impedance information, ventilation
information, oxygenation information, and end tidal carbon dioxide information.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] Various aspects of the disclosure are discussed below with reference to the accompanying
figures, which are not intended to be drawn to scale. The figures are included to
provide an illustration and a further understanding of various examples, and are incorporated
in and constitute a part of this specification, but are not intended to limit the
scope of the disclosure. The drawings, together with the remainder of the specification,
serve to explain principles and operations of the described and claimed aspects and
examples. In the figures, each identical or nearly identical component that is illustrated
in various figures is represented by a like numeral. For purposes of clarity, not
every component may be labeled in every figure. A quantity of each component in a
particular figure is an example only and other quantities of each, or any, component
could be used.
FIG. 1A is a schematic diagram of an example of a system for assisting a rescuer in
providing manual chest compressions to a victim.
FIG. 1B is a schematic diagram of an example of the compression puck from FIG. 1A.
FIG. 2A is a schematic diagram of an example of a belt-based system for providing
automated chest compressions to a victim.
FIG. 2B is a schematic diagram of an example of a piston-based system for providing
automated chest compressions to a victim.
FIG. 3A is a schematic diagram of an example of a hand-held plunger system for providing
mechanically assisted active chest compression decompression (ACD) to a victim.
FIG. 3B is a schematic diagram of an example of a cross-section of the hand-held ACD
device of FIG. 3A.
FIGS. 3C and 3D are schematic diagrams of examples of motion sensor configurations
for the hand-held ACD device of FIG. 3A.
FIG. 4 is a block diagram of hardware components of the computing device from FIGS.
1, 2A, 2B, and 3A.
FIG. 5 is a block diagram of a method of assisting a rescuer in providing resuscitative
treatment to a victim.
FIGS. 6A-6E are examples of received and processed motion sensor signals representative
of automated chest compressions.
FIGS. 7A-7E are examples of received and processed motion sensor signals representative
of the hand-held ACD device chest compressions.
FIGS. 8A-8E are examples of received and processed motion sensor signals representative
of the manual chest compressions.
FIG. 9A is an example of waveform features characteristic of automated chest compressions.
FIG. 9B is an example of waveform features characteristic of hand-held ACD device
chest compressions.
FIG. 9C is an example of waveform features characteristic of manual chest compressions.
FIG. 10 is a block diagram of an example of a decision tree to detect features characteristic
of a type of compression waveform
FIG. 11 is a block diagram of a method of selectively providing rescuer feedback.
FIG. 12 is a block diagram of an example of a system configured to synchronize delivery
of a defibrillation shock with chest compressions.
FIGS. 13A and 13B are schematic diagrams of examples of defibrillation assemblies.
FIG. 14 is a schematic diagram of an example of a defibrillator configured to provide
real-time rescuer feedback.
DETAILED DESCRIPTION
[0005] In order for a cardiac arrest victim to receive proper chest compressions with regard
to maintaining sufficient blood flow, it may be beneficial to provide real-time chest
compression feedback to a rescuer providing the chest compressions. The chest compression
feedback may allow the rescuer to adjust various aspects of the chest compressions
in order to improve patient care. Analyzed signals from a motion sensor may determine
chest compression parameters and chest compression feedback based on the determined
parameters. The motion sensor, when properly placed against the sternum of the chest
during the delivery of chest compressions, is configured to detect chest wall motion
and generate one or more signals indicative of the chest wall motion. Compressions
are considered ongoing when one or more compression cycles are immediately followed
by, or preceded by, one or more additional compression cycles performed at a resuscitative
rate. The resuscitative rate is a compression rate considered effective to induce
blood flow in a cardiac arrest victim, typically 60 to 120 compressions per minute.
[0006] The motion sensor may be disposed or otherwise incorporated within and/or communicatively
coupled to a feedback device configured to analyze the signals from the motion sensor
and provide the feedback to the rescuer. The chest compression parameters may include,
for example, a compression rate, a compression depth, and/or a decompression velocity
(e.g., a release velocity). The feedback may provide an indication of current values
for chest compression parameters, target values for chest compression parameters,
and/or recommended changes to chest compression parameters. For example, the feedback
may include indications to increase or decrease compression depth, indications to
compress at a faster or slower rate, and/or indications to quickly and completely
release the chest of the patient after each compression. In general feedback may be
corrective feedback (i.e., feedback configured to cause a rescuer to change an aspect
of the resuscitative care) and/or may be reported measurements (i.e., feedback that
indicates a value or status of an aspect of the resuscitative care without a suggested
change).
[0007] Because the chest compression parameters for manual compressions are controllable
by the rescuer delivering the compressions, the rescuer is able to respond to the
feedback and effect a change in the chest compression parameters. Additionally, because
it is common for manual chest compressions to deviate from recommended guidelines
(e.g., ACLS guidelines) due to variations in human performance (e.g., due to rescuer
inconsistencies, fatigue, etc.), feedback based on an analysis of manual chest compression
waveforms generally leads to improvements in the quality of chest compressions. For
at least this reason, rescuer feedback systems provided as stand-alone systems (e.g.,
a feedback system in a mobile device or other non-medical computing device) or as
part of medical device systems (e.g., a feedback system in or otherwise provided with
a defibrillator or other resuscitative care and/or medical device) generally include
an algorithm designed to analyze a compression waveform and determine rescuer feedback
therefrom.
[0008] Automated chest compression systems generally utilize pre-programmed values for various
chest compression parameters. For example, the manufacturer may determine these pre-programmed
values and/or a user may determine or adjust these pre-programmed values prior to
usage of the system (i.e., compression parameter values are not determined or adjusted
in real-time during chest compressions). These parameters may not be adjustable by
the rescuer during delivery of the chest compressions. Providing rescuer feedback
for non-adjustable parameters may confuse and/or cause anxiety for the rescuer, and
may undesirably lead the rescuer to interfere with the delivery of the chest compressions
in an unnecessary attempt to change these parameters. As timely and efficient delivery
of resuscitative care is crucial for patient survival, such confusion and/or distraction
on the part of the rescuer may be detrimental to the effective resuscitation of the
patient. Further, a system designed to provide feedback for one type of compressions
may generate irrelevant and/or inaccurate and misleading feedback when applied to
another type of compressions.
[0009] Thus, in order to provide a feedback system that is user-friendly and compatible
with multiple types of chest compression delivery systems, it may be beneficial for
the system to automatically identify the type of chest compressions and automatically
tailor the feedback provided to the rescuer based on the identified type of chest
compressions. Additionally, the automated determination of the type of chest compressions
by the feedback device enables the feedback device to quickly and efficiently provide
relevant and accurate feedback without requiring rescuer input and/or reconfiguration
of feedback settings and/or software and without causing rescuer confusion.
[0010] As a further benefit, automated determination of the type of chest compressions enables
the system to recognize a transition in care and adjust provided feedback accordingly.
For example, a single feedback device may provide feedback to improve manual compressions
by a first responder and then automatically detect a change to automated or mechanically
assisted compressions. For example, secondary responders, such as medical personnel
from an emergency response team or a hospital, may have equipment and training to
provide the automated and/or mechanically assisted compressions. These secondary responders
may switch the compression delivery for the patient to one of these systems. In various
medical or emergency response situations, the compressions may change one or more
times from one type of system to another. A feedback system configured to detect these
changes (e.g., as described herein) can appropriately adjust feedback and maintain
a continuity of patient records and/or resuscitative care therapies controlled and/or
recorded by the system.
[0011] Table 1 lists examples of various types of chest compressions. These various types
are discussed below in further detail in reference to FIGS. 1-3.
TABLE 1 |
TYPE OF CHEST COMPRESSIONS |
DELIVERY SYSTEM EXAMPLE |
manual chest compressions |
hands of rescuer |
mechanically assisted ACD chest compressions |
hand-held ACD device |
automated chest compressions |
belt-based system |
automated chest compressions |
piston-based system |
automated ACD chest compressions |
piston-based ACD system |
[0012] Manual chest compressions refer to classic two-hand CPR (e.g., compressions according
to Advanced Cardiac Life Support (ACLS) guidelines) where the compression parameters
(e.g., compression rate, periodicity, compression depth, release velocity, and other
compression waveform characteristics) are controlled by and subject to variability
due to physical actions of the CPR provider (e.g., the rescuer). Mechanically assisted
ACD chest compressions (e.g., delivered manually using an ACD device) refer to compressions
delivered using devices that, though mechanical in nature, depend on the physical
activity of the CPR provider to control the compression parameters. Automated chest
compressions refer to chest compressions delivered by devices that are controlled
by computerized control systems, electromechanical systems, or the like, such that
the compression parameters are predetermined by the programming or design of the device,
and are not subject to variability due to the physical actions of a CPR provider (other
than providing input to the control system or adjusting set points for an electromechanical
system, as allowed by the system). For example, the automated chest compressions may
be belt-based compressions, piston-based compressions, or piston-based ACD compressions.
[0013] Techniques are presented herein for assisting a rescuer in providing resuscitative
treatment to a victim using the various types of chest compressions. A motion sensor
placed on the sternum of the chest generates signals indicative of motion of the chest
of the victim. A computing device (e.g., processor(s) provided within a defibrillator,
medical monitor, mobile device for managing resuscitation-related activities, etc.)
receives these signals and determines or renders one or more compression waveforms.
The computing device detects features characteristic of various types of compressions
in the one or more compression waveforms. Based on these detected features, the computing
device identifies the compression waveforms as a particular type of compression waveform
(e.g., a manual compression waveform, an automated compression waveform, an ACD waveform,
etc.). The computing device controls an output device to selectively provide feedback
to the rescuer based on the identified compression waveform. A defibrillator that
includes or is controlled by the computing device may utilize the compression waveforms
to synchronize delivery of defibrillation shocks with the occurrence of specific features
in the compression waveforms. Automatically detecting the type of chest compressions
and selectively providing feedback may provide the capability of improving the effectiveness
of the resuscitation in response to the feedback. Further, the automated detection
and selective feedback may improve the versatility of the medical equipment providing
the feedback without detrimentally affecting resuscitative care. Coordinating the
timing of defibrillation shocks and phases in the chest compression cycles may further
improve the efficacy of resuscitative care.
[0014] Other capabilities may be provided and not every implementation according to the
disclosure must provide any, let alone all, of the capabilities discussed. Further,
it may be possible for an effect noted above to be achieved by means other than that
noted and a noted item/technique may not necessarily yield the noted effect.
[0015] Referring to FIG. 1A, a schematic diagram of an example of a system for assisting
a rescuer in providing manual chest compressions to a victim is shown. The manual
CPR system 100 includes a chest compression puck 110 and a computing device 160. As
shown in FIG. 1B, the chest compression puck 110 may include a motion sensor 118 and
a communications interface 116.
[0016] The motion sensor 118 is a device configured to sense motion of the chest 140 of
a victim 150 during chest compressions as applied by a rescuer 130. Although one rescuer
130 is shown in FIG. 1A, more than one rescuer may participate in resuscitation activities
for the victim 150. During chest compressions, the rescuer 130 places his or her hands
120 on the compression puck 110 and compresses and releases the chest 140 of the victim
150 along a compression axis approximately parallel to an anterior-posterior axis
195 of the victim. As discussed in more detail below in reference to FIGS. 13A and
13B, the motion sensor 118 may be a component of a defibrillation electrode assembly
and/or used in conjunction and/or coordination with a defibrillation electrode assembly.
[0017] The motion sensor 118 is configured to provide one or more signals indicative of
the motion of the chest 140 of the victim 150 to the computing device 160. The motion
sensor 118 may provide the one or more signals to the computing device 160 via a connection
170 (e.g., a wired and/or wireless connection). This connection 170 is shown as a
wired connection in FIG. 1A as an illustrative example only and not limiting of the
disclosure. The motion sensor 118 and the computing device 160 are discussed in further
detail below in reference to FIG. 4.
[0018] Referring to FIG. 2A, a schematic diagram of an example of a belt-based system for
providing automated mechanical chest compressions to a victim is shown. The belt-based
system 200 in FIG. 2A (e.g., ZOLL® AutoPulse®) includes a belt drive platform 220,
a compression belt 210, and a controller 225. The belt drive platform 220 supports
a victim in a substantially supine position at least during the chest compressions.
The compression belt 210 may include a load distribution panel 212 and pull straps
214. The pull straps 214 are configured to insert into openings 216 in the belt drive
platform 220 on either side of the victim. A drive spool (not shown), a motor (not
shown), and associated electrical and mechanical components are disposed within the
belt drive platform 220. The pull straps 214 wrap around the drive spool. The motor
moves the drive spool such that the pull straps 214 may wrap and unwrap from the drive
spool in order for the compression belt 210 to provide and release the chest compressions.
The controller 225 may include a processor, a memory, and a communications interface.
The controller 225 controls the motor and the associated electrical and mechanical
components to control the chest compressions delivered by the compression belt 210.
The controller 225 may transmit and/or receive information to and/or from an external
computing device via the communications interface.
[0019] The compression belt 210 may include the motion sensor 118. In an implementation,
the motion sensor 118 may be coupled to the compression belt 210. The motion sensor
118 may send one or more signals indicative of the motion of the chest of the victim
to the controller 225 via a wired and/or wireless connection. In various implementations,
the motion sensor 118 and/or the controller 225 may send the one or more signals indicative
of the motion of the chest of the victim to the computing device 160. The motion sensor
118 may provide the one or more signals to the computing device 160 via the connection
170 (e.g., a wired and/or wireless connection). This connection 170 is shown as a
wired connection in FIG. 2A as an illustrative example not limiting of the disclosure.
As discussed in more detail below in reference to FIGS. 13A and 13B, the motion sensor
118 may be a component of a defibrillation electrode assembly and/or used in conjunction
and/or coordination with a defibrillation electrode assembly.
[0020] Referring to FIG. 2B, a schematic diagram of an example of a piston-based system
for providing automated mechanical chest compressions to a victim is shown. The automated
piston-based CPR system 260 in FIG. 2B (e.g., the LUCAS® Chest Compression System)
includes support arms 280, a backboard 283, a control unit 286, a motor housing 287,
and a piston 288.
[0021] The control unit 286 is suspended above the chest of the victim by the support arms
280. The chest of the victim is supported by the backboard 283 and the victim is in
a substantially supine position at least during the chest compressions. The control
unit 286 may include a user input panel and/or status indicators for operations and/or
components. One end of the piston 288 is coupled to a motor (not shown) within the
motor housing 287. An opposite end of the piston 288 includes a compression pad 289.
The compression pad 289 is in contact with the chest of the victim during chest compressions
and decompressions. The control unit 286 sends a signal to the motor to control operations
of the motor. The motor functions to drive the piston 288 towards the chest of the
victim during downstroke of the chest compressions. The motor further functions to
retract the piston 288 away from the chest of the victim during upstrokes of the chest
compressions. The piston 288 moves along a compression axis substantially parallel
to the anterior-posterior axis 295.
[0022] During operation, the compression pad 289 may contact an adhesive pad 230 releasably
adhered to the skin of the victim. The adhesive pad 230 may include a liner and an
adhesive face. The liner is configured to be removed or peeled away from the adhesive
face by the rescuer in order to attach the adhesive pad 230 to the chest of the victim.
The rescuer may remove the adhesive pad 230, for example, by applying a solvent to
the adhesive pad 230 and/or peeling the adhesive pad 230 away from the patient's chest.
The motion sensor 118 may be disposed within the adhesive pad 230. The motion sensor
118 may be coupled to the computing device 160 via a wired and/or wireless connection.
As discussed in more detail below in reference to FIGS. 13A and 13B, the motion sensor
118 may be a component of a defibrillation electrode assembly and/or used in conjunction
and/or coordination with a defibrillation electrode assembly.
[0023] Referring to FIG. 3A, a schematic diagram of an example of a hand-held plunger system
for providing mechanically assisted ACD chest compressions to a victim is shown. The
system 300 includes a hand-held ACD device 310 in the hands 320 of a rescuer (not
shown). The hand-held ACD device 310 is shown held against the chest of the victim,
interposed between the rescuer's hands and the victim's chest. The configuration and
geometry of the hand-held ACD device 310 may enable the rescuer to use a similar body
position and compression technique as in manual chest compressions. As illustrated
in FIG. 3A, the hand-held ACD device 310 exerts a downward force (e.g., a force in
the downward direction 390) on the chest to actively compress the chest. The hand-held
ACD device 310 exerts an upward force (e.g., a force in the upward direction 395)
to actively decompress the chest. Suction cups, adhesive pads, and/or other components
configured to removably attach the hand-held ACD device 310 to the chest may enable
the exertion of the upward force by the hand-held ACD device 310.
[0024] The hand-held ACD device 310 is configured to provide active compression and active
decompression of the chest, to further enhance circulation throughout the body. For
instance, active compression results in the application of positive intrathoracic
pressure, leading to the ejection of blood out of the ventricles and away from the
heart. Active decompression, on the other hand, results in the application of negative
intrathoracic pressure, which enhances venous return back to the heart. In the absence
of active decompression, the chest passively returns to its neutral position during
the release phase (i.e., the decompression phase) of the chest compression cycle.
The neutral position is defined as a position of the sternum when no force, either
upward or downward, is applied to the chest. The exertion of the upward force (i.e.,
the active decompression) may increase the release velocity associated with the decompression
as compared to the release velocity without active decompression. Such an increase
in the release velocity may increase the negative intrathoracic pressure and thereby
enhance venous flow into the heart and lungs from the peripheral venous vasculature
of the patient. In other words, the active decompression may enhance venous return
of blood to the heart to refill the cardiac chambers. The active decompression may
also enhance ventilation in the patient's lungs.
[0025] Referring to FIG. 3B, a schematic diagram of an example of a cross-section of the
hand-held ACD device of FIG. 3A is shown. The hand-held ACD device 310 includes a
handle 350, an applicator body 360, and a coupling surface 364. The coupling surface
364 may include one or more suction cups 365. The coupling surface 364 may contact
a compression target pad 330 releasably affixed to the skin 380 of the patient. The
applicator body 360 is configured to releasably attach to the coupling surface 364.
For example, a coupling assembly 366 may releasably attach the applicator body 360
to the coupling surface 364. The coupling assembly 366 may include, for example, but
not limited to, a magnetic coupling assembly, a ball and socket joint, a cantilevered
arm, or a detent mechanism. The coupling assembly may be configured to provide a consistent
release force over a range of operating conditions. Further, the coupling assembly
may enable the applicator body 360 to separate from the coupling surface 364 if the
upward force exceeds a desired force (e.g., the desired force may be a maximum force
to reduce damage to the patient's skin). The hand-held ACD device 310 may further
include one or more force sensors 362 and/or one or more pressure sensors and a battery
and associated circuitry (not shown). The spring 367 may function as a component of
a pressure gauge and/or as a shock absorber to help prevent the rescuer from applying
an excessive force to the chest of the patient.
[0026] During a compression phase of a CPR chest compression cycle, the rescuer may push
on the handle 350 of the hand-held ACD device 310 in the downward direction 390. The
downward force exerted by the hand-held ACD device 310 on the chest may be sufficient
to compress the chest and induce arterial blood circulation by ejecting blood from
cardiac chambers. During the active decompression, the rescuer may pull on the handle
350 of the hand-held ACD device 310 in the upward direction 395. The downward and
upward strokes may be repeated (i.e., multiple CPR chest compression cycles with each
cycle including a downward stroke and an upward stroke) at a rate determined to optimally
enhance blood circulation and ventilation.
[0027] The motion sensor 118 may be disposed within the hand-held ACD device 310 and/or
the rescuer's hands 320 may hold the motion sensor 118. For example, the rescuer may
hold the motion sensor 118 against the handle 350 during use of the hand-held ACD
device 310. Additionally or alternatively, the motion sensor 118 may be disposed on
the chest of the patient as described below with regard to FIGS. 3C and 3D.
[0028] Referring to FIGS. 3C and 3D, schematic diagrams of examples of motion sensor configurations
for the hand-held ACD device of FIG. 3A are shown. As shown in FIG. 3C, during operation,
the coupling surface 364 may cover and surround the motion sensor 118 disposed on
the chest of the victim. The motion sensor 118 may be coupled to the computing device
160 via the connection 170 (e.g., a wired and/or wireless connection). Alternatively,
as shown in FIG. 3D, the motion sensor 118 may be disposed within the compression
target pad 330. The compression target pad 330 may be an adhesive pad, for example,
the adhesive pad 230 as described above. The compression target pad 330 may be releasably
adhered to the skin 380 of the victim. During operation, the coupling surface 364
may contact the compression target pad 330. The configuration of FIG. 3D provides
an advantage of eliminating interference of any wires from the motion sensor 118 with
the operation of the one or more suction cups 365. As discussed in more detail below
in reference to FIGS. 13A and 13B, the motion sensor 118 may be a component of a defibrillation
electrode assembly and/or used in conjunction and/or coordination with a defibrillation
electrode assembly.
[0029] In an implementation, the hand-held ACD device may include multiple motion sensors
configured to measure upward and downward motion of the chest. For example, a first
motion sensor (e.g., the motion sensor disposed in the hand-held device and/or in
the rescuer's hands) may measure the downward acceleration of the chest during compression.
A second motion sensor (e.g., the disposed on the chest) may be positioned near the
suction cup of the hand-held ACD device and may measure the upward acceleration of
the chest during active decompression.
[0030] A surface of the compression target pad 330 may include a layer of high-traction
or anti-slip material to enable the compression target pad 330 to remain attached
to the patient's skin 380 during CPR treatment. The dimensions of compression target
pad 330 may be based on a desired contact area with the patient's chest. For example,
a larger area of the compression target pad 330 may increase an amount of chest expansion
as compared to a smaller area of the compression target pad 330. As another example,
a pediatric adhesive pad may be smaller than an adult adhesive pad. The thickness
of the compression target pad 330 may depend on a resiliency of materials that form
the compression target pad 330. The shape of the compression target pad 330 may vary
based on expected chest contours for potential victims.
[0031] The hand-held ACD device 310 described above is an example of a mechanically assisted
compression device. An automated system may also provide ACD chest compressions. For
example, referring again to FIG. 2B, the compression pad 289 of the piston-based compression
device may include one or more suction cups or other mechanical devices configured
to pull up on the chest of the victim during the release phase of the CPR cycle. In
this case, the piston-based compression device may provide automated ACD chest compressions.
[0032] Referring to FIG. 4, a block diagram of hardware components of the computing device
from FIGS. 1-3 is shown. The computing device 160 may be for example, but not limited
to, a personal computer, a laptop computer, a mobile device, a hand-held device, a
wireless device, a tablet, a medical device, a defibrillator, a patient monitor, a
wearable device (e.g., a wrist-worn device, a head-worn device, etc.), or combinations
thereof. The computing device 160 may be a group of communicatively coupled devices.
Claimed subject matter is not limited to a particular type, category, size, etc. of
computing device. The computing device 160 may include a processor 162, a memory 164,
an output device 168, and a communications interface 166. As described in further
detail below, with regard to FIGS. 13A and 13B, in an implementation, the computing
device 160 may be a defibrillator. The computing device 160 may include a user input
device (e.g., a touch screen, a keyboard, a mouse, joystick, trackball, or other pointing
device, a microphone, a camera, etc.).
[0033] The processor 162 is a physical processor (i.e., an integrated circuit configured
to execute operations on the computing device 160 as specified by software and/or
firmware). The processor 162 may be an intelligent hardware device, e.g., a central
processing unit (CPU), one or more microprocessors, a controller or microcontroller,
an application specific integrated circuit (ASIC), a general-purpose processor, a
digital signal processor (DSP), or other programmable logic device, a state machine,
discrete gate or transistor logic, discrete hardware components, or any combination
thereof designed to perform the functions described herein and operable to carry out
instructions on the computing device 160. The processor 162 utilize various architectures
including but not limited to a complex instruction set computer (CISC) processor,
a reduced instruction set computer (RISC) processor, or a minimal instruction set
computer (MISC). In various implementations, the processor 162 may be a single-threaded
or a multi-threaded processor. The processor 162 may be one or more processors and
may be implemented as a combination of computing devices (e.g., a combination of DSP
and a microprocessor, a plurality of microprocessors, one or more microprocessors
in conjunction with a DSP core, or any other such configuration). The processor 162
may include multiple separate physical entities that may be distributed in the computing
device 160. The processor 162 is configured to execute processor-readable, processor-executable
software code containing one or more instructions or code for controlling the processor
162 to perform the functions as described herein.
[0034] The processor 162 is operably coupled to the memory 164. The memory 164 refers generally
to any type of computer storage medium, including but not limited to RAM, ROM, FLASH,
disc drives, fuse devices, and portable storage media, such as Universal Serial Bus
(USB) flash drives, etc. The USB flash drives can store operating systems and other
applications. The USB flash drives can include input/output components, such as a
wireless transmitter and/or USB connector that can be inserted into a USB port of
another computing device. The memory 164 may be long term, short term, or other memory
associated with the computing device 160 and is not to be limited to any particular
type of memory or number of memories, or type of media upon which memory is stored.
The memory 164 includes a non-transitory processor-readable storage medium (or media)
that stores the processor-readable, processor-executable software code.
[0035] The communications interface 166 may transmit and/or receive information from and/or
to one or more computing devices external to the computing device 160. The communications
interface 166 may transmit and/or receive the information via a wired and/or a wireless
communicative connection to the one or more external computing devices via a network
410. The information may include information stored in the memory 164 of the computing
device 160. The information may include, for example, but not limited to, resuscitative
treatment information, patient information, rescuer information, location information,
rescue and/or medical treatment center information, etc. The resuscitative treatment
information may include an indication of the identification of the compression waveform.
The network 410 may be, for example, but not limited to, a local area network, a cellular
network, and/or a computer network (e.g., an Internet Protocol network). The communications
interface 166 may provide Wi-Fi, Bluetooth®, satellite, and/or cellular communications
capabilities. The one or more external computing devices may include a server 420a
and/or another computing device 430a (e.g., a personal computer, a laptop computer,
a mobile device, a hand-held device, a wireless device, a tablet, a medical device,
a defibrillator, a patient monitor, a wearable device (e.g., a wrist-worn device,
a head-worn device, etc.), or combinations thereof. The server 420a may be a cloud
server or central facility server. The one or more external computing devices may
additionally and/or alternatively include a server 420b and/or a computing device
430b associated with a medical provider 440 (e.g., a hospital, a physician's office,
a medical records office, an emergency services office, an emergency services vehicle,
a dispatch center, etc.).
[0036] The output device 168 may be a one or more of a display, a speaker, and a haptic
device. The display may provide a graphical user interface (GUI). The display may
be, for example, but not limited to, a liquid crystal display (LCD) and/or a light
emitting diode (LED) display. In an implementation the output device 168 may be an
input/output device capable of capturing user input (e.g., a touch screen). The processor
162 may control the output device 168 to provide one or more of visible feedback,
audible feedback, haptic feedback, numerical feedback, and graphical feedback. The
feedback may include chest compression parameter feedback and/or resuscitative care
feedback. Alternatively, or additionally, the processor 162 may control the output
device 168 to provide instructions, alarms, treatment event reminders, treatment event
timing information, and/or combinations thereof. The processor 162 may further control
the output device 168 to provide resuscitative care prompts and/or instructions for
the rescuer. For example, the resuscitative care prompts may include one or more of
a prompt to start resuscitative treatment, a prompt to determine if the victim requires
CPR, a prompt to start the manual chest compressions, a prompt to determine if the
rescuer wants to provide the automated chest compressions, a prompt to attach an automated
chest compression device to the victim, and a prompt to determine if the rescuer wants
to continue CPR.
[0037] The output device 168 may be a component of the computing device 160. Alternatively,
or additionally, the output device 168 may be a discrete component communicatively
coupled to the computing device 160. The communicative coupling between the output
device 168 and the computing device 160 may be include wired and/or wireless connections.
[0038] The components 162, 164, 166, and 168 are communicatively coupled (directly and/or
indirectly) to each other for bi-directional communication. Although shown as separate
entities in FIG. 4, the components 162, 164, 166, and 168 may be combined into one
or more discrete components and/or may be part of the processor 162. The processor
162 and the memory 164 may include and/or be coupled to associated circuitry in order
to perform the functions described herein.
[0039] The motion sensor 118 may be an accelerometer and the one or more signals indicative
of the motion of the chest 140 of the victim 150 may be acceleration signals. The
accelerometer may be a single accelerometer configured to detect and measure acceleration
of the compression puck 110 along the compression axis approximately parallel to the
anterior-posterior axis 195 of the victim 150. Alternatively, the motion sensor 118
may include two or three accelerometers. The two or three accelerometers may form
a multi-accelerometer assembly or may be separate accelerometers. The two or three
accelerometers may be configured to detect and measure acceleration of the compression
puck 110 along two or three orthogonal axes with at least one of the orthogonal axes
approximately parallel to the compression axis. The acceleration signals correspond
to acceleration of the chest 140, at least along the compression axis, during the
chest compressions. In various implementations, the motion sensor 118 may be one or
more of a velocity sensor, a displacement sensor, and a force sensor.
[0040] The connection 170 between the motion sensor 118 and the computing device 160 is
shown as a wired connection in FIG. 4. However, this is an illustrative example only
and not limiting of the disclosure. The motion sensor 118 may provide the one or more
signals indicative of the chest motion to the computing device 160 via a wired and/or
wireless connection. The motion sensor 118 may be disposed, for example, in the compression
puck 110, the compression belt 210, the adhesive pad 230, the compression target pad
330, or the hand-held ACD device 310. As a further example, and as discussed in more
detail below in reference to FIGS. 13A and 13B, the motion sensor 118 may be a component
of a defibrillation electrode assembly.
[0041] In the above examples, the motion sensor 118 is physically separate from the computing
device 160. However, in various implementations, the computing device 160 may be a
compression monitor, a smart-phone or other hand-held device, and/or a wearable device.
In these cases, the computing device 160 may include the motion sensor 118 (e.g.,
the motion sensor 118 may be a component of or physically attached to the computing
device 160). For example, the computing device 160 may be a cell phone that includes
the motion sensor 118, configured to be held in between the hands of the rescuer during
manual CPR compressions.
[0042] Referring to FIG. 5, a method of assisting a rescuer in providing resuscitative treatment
to a victim is shown. The method 500 is, however, an example only and not limiting.
The method 500 can be altered, e.g., by having stages added, removed, rearranged,
combined, and/or performed concurrently.
[0043] At stage 510, the method 500 includes receiving signals from a motion sensor. For
example, the processor 162 is configured to receive the one or more signals indicative
of the motion of the chest from the motion sensor 118. In an implementation, the motion
sensor 118 may be an accelerometer and the one or more signals may be acceleration
signals. The processor 162 may receive the acceleration signals as shown, for example,
in FIG. 6A for automated chest compressions, FIG. 7A for hand-held ACD device chest
compressions, and FIG. 8A for manual chest compressions. In all of these figures,
the x-axis corresponds to time and the y-axis corresponds to a signal magnitude.
[0044] Referring again to FIG. 5, at stage 520, the method 500 includes generating a compression
waveform based on the received signals. For example, the processor is configured to
generate one or more compression waveforms based on the one or more signals indicative
of the motion of the chest as received from the motion sensor 118. The processor 162
may apply a filter (e.g., a high-pass filter configured to remove a baseline) to the
acceleration signals to determine a filtered acceleration waveform as shown, for example,
in FIG. 6B for automated chest compressions, FIG. 7B for hand-held ACD device chest
compressions, and FIG. 8B for manual chest compressions. In these examples, the filter
is a high pass filter however other filters are within the scope of the disclosure.
The processor 162 may integrate the acceleration waveform once to determine a velocity
waveform. Examples of velocity waveforms are shown in FIG. 6C for automated chest
compressions, FIG. 7C for hand-held ACD device chest compressions, and FIG. 8C for
manual chest compressions. The processor 162 may integrate the acceleration waveform
twice to determine a displacement waveform. Examples of displacement waveforms are
shown in FIG. 6D for automated chest compressions, FIG. 7D for hand-held ACD device
chest compressions, and FIG. 8D for manual chest compressions.
[0045] At stage 530, the method 500 includes identifying the compression waveform as one
of a manual chest compression waveform, an automated chest compression waveform, and
an ACD chest compression waveform. For example, the processor 162 may evaluate the
compression waveform for quantitative and/or qualitative features characteristic of
a particular compression delivery system. The processor 162 is configured (e.g., based
on instructions stored in the memory 164 and/or the hardware topology of the processor
and associated circuitry) to detect waveform features characteristic of one or more
of a manual chest compression waveform, an automated chest compression waveform, an
automated ACD chest compression waveform, and an ACD chest compression waveform. Based
on the detected features, the processor 162 may identify the type of compression waveform
(e.g., a manual chest compression waveform, an automated chest compression waveform,
an ACD chest compression waveform, etc.).
[0046] The processor 162 may detect the characteristic features based on identified compression
cycles in the compression waveform. In order to identify the compression cycles, the
processor 162 may apply signal analysis methods to the compression waveform. The processor
162 may apply the signal analysis to identify the beginning and end of each compression
cycle within the compression waveform. The processor 162 may further apply the signal
analysis to identify various portions of one or more of the compression cycles (e.g.,
various phases of the compression cycle such as the downstroke, the upstroke, etc.).
The processor 162 may apply the signal analysis to the acceleration waveform, the
velocity waveform, the displacement waveform, and/or combinations thereof. As an example,
the signal analysis may include one or more of band pass filtering, rectification,
and/or threshold analysis. The threshold analysis may distinguish features in the
compression waveforms due to compressions from features in the compression waveforms
due to noise and/or motion of the patient and/or the motion sensor not caused by compressions
(e.g., vibrations of a gurney and/or an ambulance). The threshold analysis may compare
peaks in a signal to a threshold amplitude. Peaks in the measured signal that are
below the threshold amplitude may correspond to the noise and/or the motion of the
patient and/or the motion sensor not caused by compressions. Examples of compression
detection waveforms from the velocity waveforms are shown in FIG. 6E for automated
chest compressions, FIG. 7E for hand-held ACD device chest compressions, and FIG.
8E for manual chest compressions. Using the threshold analysis, the processor 162
may identify individual compression cycles within a series of compression cycles from
the velocity waveform. The threshold analysis determines differences between a waveform
magnitude sampled over a sample time interval and a threshold magnitude. Additionally,
the threshold analysis determines differences in the waveform magnitude sampled between
sample time intervals. In this manner, the threshold analysis may identify the beginning
and the end of each compression cycle in the series of compression cycles. As discussed
herein, a single chest compression cycle includes a downstroke and an upstroke. The
downstroke may also be referred to as a compression phase of the CPR cycle. The upstroke
may also be referred to as a release phase and/or a decompression phase of the CPR
cycle.
[0047] Once the processor 162 identifies the compression cycles within the waveforms, the
processor 162 may detect waveform features characteristic of various types of chest
compressions. For example, the various types of chest compressions may include those
listed above in Table 1.
[0048] Referring to FIGS. 9A, 9B, and 9C, examples of waveform features characteristic of
automated chest compressions, manual chest compressions, and hand-held ACD device
chest compressions, respectively, are shown. The compression depth (feature 901) is
a measure of chest displacement as indicated by the peak to trough amplitude difference
on a displacement waveform within a compression cycle. The compression rate (feature
902) is a number of compression cycles per unit time. The hold time (feature 903)
is a time interval within the compression cycle between the downstroke and the successive
upstroke. The velocity minimum-to-maximum time (feature 904) is the time interval
on the velocity waveform from a velocity waveform trough to a successive velocity
waveform peak within the compression cycle. The velocity amplitude (feature 905) is
the difference on the velocity waveform between the amplitude of a velocity waveform
peak and the amplitude of a successive velocity waveform trough. The compression width
(feature 906) is the time interval between the onset of a compression and the end
of a compression (i.e., the time interval between the start of the downstroke and
the end of the upstroke for the compression cycle). The relaxation time (feature 907)
is the time interval between compression cycles (i.e., the time interval between the
end of the upstroke of a first compression cycle and the start of the downstroke for
a second, successive compression cycle). The release time (i.e., the decompression
time) (feature 908) is the time interval from the beginning to the end of an upstroke.
Features 901, 902, 903, 906, 907, and 908 are indicated on the velocity waveforms
in FIGS. 9A-9C as illustrative examples. The processor 162 may evaluate these features
on one or more of the displacement waveform, the velocity waveform, and the acceleration
waveform. The processor 162 may select the particular waveform for evaluation based
on the clarity of the features in the selected waveform as compared to the other waveforms
and/or as compared to signal noise.
[0049] For each of the features discussed in FIGS. 9A-9C, expected values or ranges of values
for these features may be associated with the particular types of the chest compressions.
Examples, not limiting of the disclosure, of values and value ranges for the features
discussed above are shown below in Table 2 for automated belt-based compressions and
for manual compressions. Other values are consistent with the disclosure and the examples
given below are not limiting.
TABLE 2 |
COMPRESSION WAVEFORM FEATURES |
Compression Type |
Belt-based |
Manual |
Compression Rate |
77-83 cpm |
<206 cpm |
(901) |
Compression Depth |
1-6 inches |
0.33-7 inches |
(902) |
(2.5-15 cm) |
(0.84-17.7 cm) |
Hold Time |
≥ 120 msec |
≤600msec |
(903) |
Velocity Minimum-to-Maximum Time |
120-480 msec |
Not evaluated |
(904) |
Velocity Amplitude |
>295 |
250-10000 |
(905) |
Compression Width |
<562.5 msec |
30-1300 msec |
(906) |
Relaxation Time |
>300 msec |
Not evaluated |
(907) |
Release Time |
Not evaluated |
≤800 msec |
(908) |
In an implementation, one or more of the values or ranges shown above in Table 2 may
serve as threshold values or ranges for identification of the type of compression
waveform. For example, if the measured compression rate on the waveform is less than
77 cpm or greater than 83 cpm, then the measured waveform does not correspond to the
belt-based compressions. Conversely, if the measured compression rate is greater than
or equal to 77 cpm and less than or equal to 83 cpm, then the measured waveform does
correspond to the belt-based compressions. As a further example, if the measured hold
time is less than 120 msec, then the measured waveform does not correspond to the
belt-based compressions. Conversely, if the measured hold time waveform is greater
than or equal to 120 msec, then the measured waveform corresponds to the belt-based
compressions. The processor 162 may evaluate the features according to Table 2 to
distinguish the belt-based compression waveform from the manual compression waveform
and to distinguish the manual compression waveform from signal noise. Some of the
listed features may not provide a detectable difference between types of waveforms.
Thus the processor 162 is configured to determine a subset of features (e.g., one
or more of the listed features) to evaluate in order to identify the compression waveform.
In the example above, the release time 908 is not evaluated to distinguish belt-based
compressions from manual compressions. Similarly, the velocity minimum-to-maximum
time 904 and the relaxation time 907 are not evaluated to distinguish the manual compression
waveform from noise. Other subsets of evaluated features are consistent with the disclosure
as Table 2 provides an example only of evaluated features.
[0050] Referring again to FIG. 9B, in an implementation, the processor 162 may evaluate
a waveform shape to detect shape features characteristic of a type of chest compression
waveform. As shown in FIG. 9B, the velocity waveform may exhibit a shoulder feature
910. This shoulder feature 910 may be characteristic of the hand-held ACD device waveform
and an automated ACD device waveform. For example, the spring and/or the suctions
cups in ACD devices may introduce fluctuations in the acceleration signal (e.g., as
indicated by feature 916 in FIG. 9B) on top of variations in the acceleration signal
due to the chest compressions. In this example, the shoulder feature 910 precede a
peak in the velocity waveform. In an implementation, the processor 162 may identify
the shoulder feature 910 based on a change in slope of the waveform. The change in
slope is shown schematically as a first slope 912a that changes to a second slope
912b and then changes again to a third slope 912c. The second slope 912b may be less
than the first slope 912a and the third slope 912c. The processor 162 may quantify
the shoulder feature 910, for example, according to the values of the slopes 912a,
912b, and 912c, the differences in these slopes, and/or the width 914 of the shoulder
feature 910. In this manner, the processor 162 may distinguish the shoulder region
characteristic of the hand-held ACD device from a shoulder in a waveform for a different
type of chest compression due to noise in the waveform. Similarly, the processor 162
may distinguish the shoulder region characteristic of the hand-held ACD device from
a monotonic change in amplitude associated with another type of chest compression.
[0051] In further reference to FIG. 9B, during ACD chest compressions (e.g., mechanical
ACD and mechanically assisted ACD), the patient's sternum is typically pulled upward
beyond the neutral position of the sternum. Thus, the compression phase and decompression
phase will both have a portion of motion during which the sternum is pulled upward
beyond the neutral position. This portion of motion corresponds to an elevated phase.
As shown in FIG. 9B, the ACD displacement waveform includes four phases in reference
to the neutral position (NP) 920, e.g., compression elevated (CE) phase 930, compression
non-elevated (CN) phase 935, decompression elevated (DE) phase 940, and decompression
non-elevated (DN) phase 945. As a result, in order to determine chest compression
depth during ACD compressions, a waveform analysis algorithm implemented by the processor
162 includes an identification of the compression neutral point 920. In an implementation,
the algorithm may set a pre-compression neutral point as the initial position of the
chest prior to an initiation of chest compressions. However, due to chest remodeling
that typically occurs during chest compressions, the pre-compression neutral point
may change over the course of applied chest compressions. Chest remodeling generally
refers to changes in the anterior/posterior diameter of the patient's chest based
on a combination of an applied force during the chest compressions and a compliance
of the patient's chest. Chest compliance is the mathematical description of the tendency
of the chest to change shape as a result of the applied force. Thus, compression depth
feedback based on the pre-compression neutral point is likely to be inaccurate.
[0052] In order to provide accurate compression depth feedback, the processor 162 may be
configured to dynamically determine the compression neutral point 920 to account for
changes in the compression neutral point 920 over the course of chest compressions.
To this end, the waveform analysis algorithm may need additional information such
as compression force information (e.g., as provided by the one or more force sensors
362 in the ACD device), motion information for the elevated and non-elevated phases,
and chest compliance information. The chest compliance information may be a mathematical
relationship between displacement, force, and chest compliance. The processor 162
may determine accurate compression depth feedback for ACD compressions based on the
dynamically determined compression neutral point 920. The compression depth feedback
based on the dynamically determined compression neutral point 920 may include the
compression non-elevated depth 950 (e.g., the CN depth) and the decompression elevated
height 960 (e.g., the DE height).
[0053] Referring to FIG. 10, a block diagram of an example of a decision tree to detect
features characteristic of a type of compression waveform is shown. In this example,
at stage 1030 of the decision tree 1000, the processor 162 evaluates the waveform
shape for features characteristic of ACD chest compressions (e.g., automated ACD compressions
and hand-held device ACD compressions). As discussed above, the waveform for ACD chest
compressions may include the shoulder feature 910. If the processor 162 determines
that the waveform includes the shape characteristic of ACD chest compressions (e.g.,
the shoulder feature 910), then the decision tree branches to the stage 1040, otherwise
the decision tree branches to the stage 1060.
[0054] At the stages 1040 and 1060, the processor 162 may evaluate a compression rate variability.
In an implementation, the processor 162 may measure a variability of one or more of
the features 901, 902, 903, 904, 905, 906, 907, and 908 over a multiple compression
cycles. The measured variability may be, for example, a range, a standard deviation,
or another measure of the variation associated with a feature value over multiple
compression cycles. The processor 162 may compare the variation of a feature over
a number of compression cycles to a predetermined threshold criterion. The processor
162 may identify the compression type based on the comparison or may eliminate a candidate
compression type based on the criterion. For example, if the variation is below the
threshold criterion, the processor 162 may identify a first compression delivery system
and if the variation is above the threshold criterion, the processor 162 may identify
a second compression system. As another example, if the variation is below the threshold
criterion, the processor 162 may identify a first type of compression and if the variation
is above the threshold criterion, the processor 162 may rule out the first type of
compression without identifying a second type of compression. The processor 162 may
utilize an additional criterion to identify the second type of compression. For example,
the belt-based system in FIG. 2A may be configured (e.g., according to a chest compression
rate specification for the system) to deliver a compression rate of 80 cpm. In practice,
the belt-based system may deliver a compression rate is in a range from 77-83 cpm
over two or more compression cycles. Thus, in this example, the variability of the
compression rate is approximately 4% (e.g., the compression rate is 80 cpm +/- 4%).
As another example, the piston-based system in FIG. 2B may be configured to deliver
a compression rate of 100 cpm. In practice, the piston-based compression device may
deliver a compression rate is in a range from 95-105 cpm over two or more compression
cycles. Thus, in this example, the variability of the compression rate is approximately
5% (e.g., the compression rate is 100 cpm +/- 5%). In contrast, the waveform from
manual compressions may exhibit a compression rate that varies by 15%-50%. In general,
automated chest compression devices deliver a more consistent compression rate (i.e.,
lower variability) than manual chest compressions. Therefore, a threshold value for
variability (e.g., a threshold variability as determined based on an operation specification
for the automated chest compression devices) may serve to distinguish the automated
chest compression waveform (e.g., automated ACD or automated non-ACD) from the manual
chest compression waveform.
[0055] Referring again to FIG. 10, at the stage 1040, the processor 162 may evaluate the
compression rate variability to distinguish between the mechanically assisted ACD
compression waveform and the automated ACD compression waveform. At the stage 1060,
the processor 162 may evaluate the compression rate variability to distinguish between
the automated compression waveform and the manual compression waveform.
[0056] In this example, if the variability is low (e.g., <15%), then, at the stage 1045
the processor 162 may identify the chest compressions as automated ACD device chest
compressions. If the variability is high (e.g., ≥15%), then, at the stage 1047, the
processor 162 may identify the chest compressions as hand-held ACD device compressions.
Similarly, if the variability is low (e.g., <15%), then, at the stage 1065, the processor
162 may identify the chest compressions as automated chest compressions. If the variability
is high (e.g., ≥15%), then, at the stage 1070, the processor 162 may identify the
chest compressions as manual chest compressions.
[0057] Optionally, at the stage 1080, the processor 162 may further identify the compression
waveform as corresponding to a particular type of automated compression device based,
for example, on an operational specification of the automated system. Thus, at the
stage 1085, the processor 162 may compare the characteristics of the compression waveform
to operational specifications of one or more automated chest compression systems to
identify the automated chest compression system delivering the chest compressions
to the patient. For example, the ZOLL® AutoPulse® is configured to deliver chest compressions
at 80 cpm whereas the LUCAS® chest compression system is configured to deliver chest
compressions at 100 cpm. Thus, at the stage 1095, the processor 162 may identify the
compression waveform as a ZOLL® AutoPulse® compression waveform based on the compression
rate (e.g., feature 902 as discussed above) of 80 cpm. At the stage 1097, the processor
162 may identify the compression waveform as a LUCAS® chest compression system waveform
based on the compression rate (e.g., feature 902 as discussed above) of 100 cpm. The
ZOLL® AutoPulse® and LUCAS® chest compression system are examples only of particular
types of automated compression devices and are not limiting of the disclosure. Similarly,
the values of 80 cpm and 100 cpm are examples only of specific operational specifications
and are not limiting of the disclosure.
[0058] In addition to the waveform features and shapes discussed above, the processor 162
may evaluate other waveform parameters to identify the type of compression waveform
and the type of chest compressions. For example, the processor 162 may evaluate a
consistency of waveform shapes by applying an autocorrelation function to the waveform
peaks. For example, the waveform peaks for automated chest compressions may produce
a high degree of autocorrelation as compared to the waveform peaks for manual chest
compressions. As a further example, the processor 162 may compare waveform peak amplitudes
with a threshold value to distinguish peaks due to chest compressions from peaks due
to noise in the motion sensor signal. In general, peak amplitudes due to chest compressions
are higher than those found in a noise signal.
[0059] Referring again to FIG. 5, at stage 540, the method 500 includes controlling an output
device to selectively provide compression feedback to the rescuer based at least in
part on the identified chest compression waveform. In various implementations, selectively
providing feedback may include changing displayed values of compression parameters,
altering a configuration of a display screen, changing tones or other parameters of
audible feedback, adding or deleting parameters to or from a set of feedback parameters,
and/or changing colors or other parameters of the display screen. The processor 162
may implement these changes based on the identified type of compressions.
[0060] The compression feedback may include an indication of a measured compression parameter.
Further, the compression feedback may include an indication of a comparison of the
measured compression parameter to a target and/or an indication of a suggested change
to the measured compression to reach the target. For example, the processor 162 may
control the output device 168 so that one or more compression parameter values are
not displayed or otherwise provided to the rescuer. As a further example, the processor
162 may control the output device 168 to stop delivery of voice prompts, text prompts
(i.e., written messages on the display screen), metronome prompts, and/or visual display
color change prompts. Additionally, or alternatively, the processor 162 may control
the output device 168 to not provide graphic indications of the measured parameters
and/or graphic indications of a comparison between the measured parameter and the
target. For example, a geometric shape such as a rectangle, circle, or diamond that
fills to indicate a comparison of the measured parameter to the target may remain
filled or unfilled but not display any changes or may not be displayed. As another
example, a pulsating graphic may remain still or may not be displayed. In this manner,
the processor 162 may withhold compression feedback. (i.e., the processor 162 does
not display or otherwise provide indications of the feedback to the rescuer). However,
the processor 162 may or may not determine the feedback when the processor 162 does
not provide the feedback. Thus withholding feedback does not imply that the feedback
exists in and/or is known to the memory 164 and/or the processor 162.
[0061] In an implementation, the processor 162 may control the output device 168 to provide
values of the measured parameters along with an indication of the identified type
of compression waveform. The processor 162 may control the output device 168 to change
one or more output characteristics of the provided parameters based on the identified
type of compression waveform. The output characteristics may include, for example,
but not limited to, the color, the font, the size, the brightness, the location, the
audible frequency, and/or the audible volume. For example, the output device 168 may
display the compression rate and depth in a dimmer manner for automated chest compressions
than for manual chest compressions in order to de-emphasize these numbers. Additionally,
the output device 168 may display, for example, "automated compression device-do not
adjust" or other indication of the identified type of compression waveform in proximity
to the dimmed compression rate and depth.
[0062] In general, selectively providing the rescuer feedback includes modifying the compression
information that the output device 168 presents as feedback. For example, the feedback
may indicate to the rescuer that the compression depth and/or the compression rate
conforms to a desired compression depth and/or compression rate. In other words, the
feedback indicates to the rescuer that the compression depth is a "good" compression
depth if the compression depth is greater than or equal to a target depth. Similarly,
the feedback indicates to the rescuer that the compression rate is a "good" compression
rate if the compression rate is greater than or equal to a target rate. The processor
162 may use the target depth and the target rate as thresholds for determining if
the measured compression depth and/or the measured compression rate are satisfactory
or in need of modification. The targets and thresholds may be single numbers or may
be a range of values. The provided feedback then indicates to the rescuer if the chest
compression parameters are satisfactory or in need of modification. In determining
the feedback, the processor 162 may modify the threshold or threshold range based
on the type of chest compression detected. For example, if the processor 162 detects
mechanical chest compressions, the compression rate threshold range corresponding
to a satisfactory compression rate may be 73-82 compressions per minute (cpm). However,
for mechanically assisted ACD compressions, the compression rate threshold range may
be 70-80 cpm and for manual compressions the compression rate threshold range may
be 100-120 cpm. The narrower range for the mechanical compressions (e.g., a range
of 9 cpm) is due to more controlled tolerance of a mechanical system as compared to
a manual system (e.g. a range of 20 cpm). The range for the mechanically assisted
ACD compressions may account for improved efficiency of compressions with mechanical
assistance as opposed to manual compressions. As another example, if the processor
162 detects mechanical compressions without ACD, the compression depth threshold range
maybe 1.25-2.5 inches (e.g., 3-7 cm) whereas the compression depth threshold range
for ACD may include separate ranges for the downstroke and the upstroke. Compression
depth and compression rate are examples only of parameters evaluated for feedback
and not limiting of the disclosure. The processor 162 may evaluate other measured
compression parameters and determine appropriate feedback.
[0063] Referring to FIG. 11, a method of selectively providing rescuer feedback is shown.
The method 1100 is, however, an example only and not limiting. The method 1100 can
be altered, e.g., by having stages added, removed, rearranged, combined, and/or performed
concurrently. The stages 510, 520, and 530 of the method 1100 are described above
in reference to FIG. 5.
[0064] At stages 1120, the processor 162 may identify the compression waveform as the mechanically
assisted ACD chest compression waveform. The selectively provided feedback for the
mechanically assisted ACD chest compression waveform depends on the use of the dynamically
determined compression neutral point 920, as determined at stage 1125. If the waveform
analysis algorithm is based on the pre-compression neutral point, then, at stage 1130
the processor 162 may control the output device 168 such that the output device 168
does not provide compression depth feedback but does provide compression rate feedback.
However, if the waveform analysis algorithm is based on the dynamically determined
compression neutral point 920, then, at stage 1135, the processor 162 may provide
compression rate and compression depth feedback. The compression depth feedback may
include chest displacement feedback for the compression non-elevated (CN) phase (e.g.,
the CN depth 950 as illustrated in FIG. 9B) and for the decompression elevated (DE)
phase (e.g., the DE height 960 as illustrated in FIG. 9B).
[0065] At stage 1140, the processor 162 may identify the compression waveform as the automated
chest compression waveform. In this case, at the stage 1150, the processor 162 may
control the output device 168 such that the output device 168 may withhold compression
depth feedback and withhold compression rate feedback. As compression depth and compression
rate are predetermined parameters for the automated belt-based device, the rescuer
cannot adjust these parameters at least during operation of the automated device.
Also, the predetermined parameters for automated compressions may differ from ACLS
guidelines for manual compressions (e.g., the compression rate for the belt-based
compression device may be 80 cpm while the ACLS recommended rate may be 100 cpm).
Feedback may confuse and/or distract the rescuer to the detriment of the resuscitative
care provided by the rescuer. Further, the feedback may cause the rescuer to attempt
to change compression parameters of the automated compression device to the detriment
of patient care.
[0066] At stage 1160, the processor may identify the compression waveform as the manual
compression waveform. In this case, at the stage 1170, the processor 162 may control
the output device 168 such that the output device 168 provides compression depth feedback
and compression rate feedback. Both compression rate and compression depth are controllable
and adjustable by the rescuer for manual compressions.
[0067] At stage 1180, the processor 162 may determine that the compression identification
is invalid. This determination may indicate that the compression type was incorrectly
identified at the stage 530. In other words, the threshold analysis and detection
function may erroneously identify waveform features as corresponding to an individual
compression. For example, the amplitudes of the waveforms may vary due to noise contributions
to the motion sensor signals. The noise contributions may be due to vibrations due
to road conditions for a patient in a vehicle, patient motion, gurney motion, vehicle
suspension vibrations, etc. In this case, the method 1100 returns to the stage 510
to receive and analyze additional signals received from the motion sensor 118.
[0068] The specific feedback provided and/or withheld as discussed above with regard to
the stages 1130, 1150, and 1170 is by way of example only. The systems described herein
may automatically determine the type of chest compressions and selectively provide
the feedback in a manner other than the examples provided.
[0069] At one or more of the stages of the methods 500 and/or 1100, the processor 162 may
store CPR parameter information in the memory 164. The processor 162 may store the
CPR parameter information during manual compressions, automated compressions and/or
mechanically assisted compressions. The CPR parameter information may include one
or more of the signals received from the motion sensor 118 and the processed waveforms
(e.g., as shown, for example, in FIGS. 6A-8E) and/or the compression parameters determined
from the waveforms. The processor 162 may store the information as an event log with
time stamps associated with various portions of the information. The stored information
may include an indication of the identified type of CPR compressions.
[0070] Referring to FIG. 12, an example of a system configured to synchronize delivery of
a defibrillation shock with chest compressions is shown. In an implementation, the
computing device 160 is a defibrillator 1210. The defibrillator 1210 includes a processor
1262 and a memory 1264. The defibrillator processor 1262 and the memory 1264 are configured
with the capabilities, structure, and functionality as described herein with regard
to the processor 162 and the memory 164, respectively. For example, the defibrillator
processor 1262 may use the chest compression parameters, for example, as measured
by the motion sensor 118 disposed in the electrode assembly, to identify the type
of chest compressions. The defibrillator processor 1262 may tailor resuscitation feedback
provided by the defibrillator 1210 to the identified type of chest compressions as
described herein with regard to the methods 500 and 1000. Additionally, the defibrillator
processor 1262 is configured to synchronize delivery of chest compressions with delivery
of the defibrillation shock by the defibrillator 1210. The efficacy of the defibrillation
shock may depend on the timing of the shock with respect to the chest compressions,
for example. The defibrillator processor 1262 may analyze the motion sensor signal
to detect various phases and timing points in the compression cycle. The phases include,
for example, the decompression phase and the compression phase. The timing points
may include, for example, a start of the decompression phase and a maximum positive
slope (e.g., dV/dt) in the velocity waveform. Based on this analysis, the defibrillator
processor 1262 may select a timing point in the compression cycle at which to deliver
the defibrillation shock. The defibrillator processor 1262 may further determine a
time interval, or delay, relative to the timing point at which to deliver the defibrillation
shock. For example, the defibrillator processor 1262 may determine the time interval
from a detection of the start of the decompression phase to initiation of delivery
of the defibrillation shock. This time interval may be a number of milliseconds (e.g.,
1-400 msec). In an implementation, the defibrillator processor 1262 may further synchronize
the delivery of the defibrillation shock with a combination of the chest compression
cycle and measured ECG activity.
[0071] In order to synchronize defibrillation with manual chest compressions and/or mechanically
assisted chest compressions, the defibrillator 1210 may provide synchronization instructions
to the rescuer 1285 via an input/output device 1250. The input/output device 1250
may be substantially as described above with regard to the output device 168.
[0072] For manual chest compressions (e.g., manual compressions 1280 delivered by the rescuer
1285 to the patient 1289), the therapeutic benefits of defibrillation shock during
the compressions may improve when combined with a shorter duration of the upstroke
phase. For example, the duration of the upstroke phase may be shorter during a synchronized
defibrillation/compression treatment than in compressions delivered without defibrillation
synchronization. An increased upstroke velocity (e.g., the release velocity) may reduce
the duration of the upstroke phase. Rescuer feedback that includes prompting (e.g.,
visual prompting and/or audible prompting) directed at the upstroke velocity may help
the rescuer to achieve the desired shorter duration of the upstroke phase.
[0073] A consideration with the synchronization of defibrillation to manual compressions
is that the defibrillation shock generates approximately 2000 volts. Touching the
patient directly during a defibrillation shock will not harm the rescuer, but it may
generate a significant amount of discomfort. In an implementation, the rescuer may
place an electrically insulating protection layer that extends over the surface of
the patient so that manual compressions may continue safely and unabated during the
defibrillation shock delivery. Alternatively, for identified manual chest compressions,
the defibrillator 1210 may provide instructions to the rescuer to stop chest compressions
prior to delivery of the shock.
[0074] In order to synchronize defibrillation with the automated chest compressions, the
defibrillator 1210 may communicate, via a wired and/or wireless connection 1215, with
an automated chest compression device 1220 (e.g., the belt-based system 200 or the
piston-based system 260). For example, the defibrillator 1210 may communicate via
an analog signal, a serial Universal Serial Bus (USB) interface, or via a low-latency
wireless protocol such as the IEEE 802.15.4 protocol standard (e.g., ZigBee®). The
defibrillator processor 1262 may control the defibrillator 1210 to deliver the defibrillation
shock at a particular point during the CPR chest compression cycle to synchronize
the defibrillation shock with the chest compressions. The synchronization may increase
the efficacy of the defibrillation shock. As an example, the defibrillator 1210 may
deliver the shock at or near the deepest point of compression.
[0075] In an implementation, the defibrillator processor 1262 is configured to control the
input/output device 1250 to provide an instruction to the rescuer to use the defibrillator
to deliver the defibrillation shock to the victim. For example, the input/output device
1250 may provide one or more of a displayed, an audible, and/or a vibration based
command for the rescuer to push a shock button on the defibrillator. The defibrillator
processor 1262 may control the input/output device 1250 to provide defibrillation
parameter feedback to the rescuer 1285. The input/output device 1250 may be a component
of the defibrillator 1210 and/or may be a separate device communicatively coupled
to the defibrillator 1210. For example, the defibrillation parameter feedback may
include one or more of shock energy information, ECG information, defibrillator equipment
status information, defibrillator data analysis status information, shock timing information,
pacer information, and chest impedance information.
[0076] The defibrillator processor 1262 may further synchronize the delivery of defibrillation
shock with compressions based at least in part on signals from the physiological sensors
1240. In an implementation, the defibrillator processor 1262 may receive input from
one or more physiological sensors 1240 configured to generate signals indicative of
physiological parameter information for the victim. The defibrillator processor 1262
may determine the physiological parameter information from the sensor signals. The
physiological sensors 1240 may include one or more of a blood pressure sensor, a blood
flow sensor, a ventilation sensor, an oxygenation sensor, and an end tidal carbon
dioxide sensor. The physiological sensors 1240 may further include the defibrillation
electrodes which may function as chest impedance sensors and/or ECG sensors. These
sensors may be individual or combined sensors. The defibrillator may provide physiological
information to the rescuer via the input/output device 1250. Alternatively, or additionally,
the defibrillator may store the physiological information and/or transmit the physiological
information to another device. The physiological information may include blood pressure
information, ECG information, blood flow information, chest impedance information,
ventilation information, oxygenation information, and end tidal carbon dioxide information.
In an implementation, the processor 162 may determine the chest compression feedback
based at least in part on the physiological parameter information. For example, chest
impedance information and/or blood flow information may indicate a sufficient or insufficient
chest release.
[0077] In an implementation, the defibrillator processor 1262 may analyze the ECG of the
patient. Based on this analysis, the defibrillator processor 1262 may determine the
time for delivery of the defibrillation shock. The efficacy of the defibrillation
shock may depend on the timing of the shock with respect to a varying state of the
heart during ventricular fibrillation (VF), for example. During VF, variations in
the state of excitability of the heart cells results in a cyclic period of increased
susceptibility to defibrillation. The susceptible period occurs when the number of
excitable cells is low, i.e., a higher state of depolarization. The ECG waveform may
be indicative of these susceptible periods and provide a basis for shock synchronization
with the ECG. The defibrillator processor 1262 may filter the ECG signal from the
patient in order to reduce compression signal artifacts in the ECG signal to improve
the accuracy of the ECG signal. In an implementation, the defibrillator processor
1262 is configured to send a signal to a controller of the automated compression device
(e.g., the controller 225 of the automated belt-based device or the control unit 286
of the automated piston-based device) to stop compressions prior to and/or during
the ECG analysis. Stopping the compressions during the ECG analysis may reduce or
eliminate signal artifacts from the chest compressions in the ECG signal.
[0078] In an implementation, the defibrillator processor 1262 may synchronize pacing with
compressions in order to augment the compressions with the electrically-induced contractions
of the myocardium. During a resuscitation, the heart is in a state of profound ischemia
resulting in a flaccidity and loss of tone as lactate builds up in the myocardium
and the tissue pH drops. As a result of the loss of tone, the heart becomes a less-effective
pump structure for generating blood flow during manual chest compressions. Drugs such
as epinephrine act to improve tone, but because they are delivered venously, their
action may take 2-3 minutes during cardiac arrest, when the only blood flow is that
induced by the chest compressions. Pacing may improve the tone of the myocardium without
the therapeutic delay experienced with drugs such as epinephrine. This improvement
in myocardial tone may substantially improve the hemodynamic effectiveness of the
compressions.
[0079] In an implementation, the defibrillator processor 1262 may synchronize compressions
and shock with delivery of ventilations by a ventilation device 1270. At the time
of defibrillation shock, it is desirable that there not be a ventilation in progress.
Preferable sequencing is for ventilation expiratory cycle to complete in the decompression
phase of the compression cycle immediately preceding the compression cycle during
which the synchronized shock takes place. The defibrillator 1210 may communicate with
the ventilation device 1270 to synchronize the delivery of ventilations with the compressions
and defibrillation shock. Alternatively, or additionally, the defibrillator 1210 may
provide ventilation prompts for a rescuer controlling the ventilation device 1270.
[0080] In an implementation, an external computing device 1290 may control the defibrillator
1210. For example, a processor of the external computing device 1290 may provide all
or a portion of the functions and capabilities of the processor 162 in lieu of and/or
in combination with the defibrillator processor 1262. In an implementation, the external
computing device 1290 may work in coordination with the defibrillator 1210. For example,
the external computing device 1290 may receive and/or transmit data to and/or from
the defibrillator and/or coordinate communications between the defibrillator 1210
and other external devices. The other external devices may include compression devices,
ventilation devices, physiological sensors, and/or input/output devices. The data
may include patient medical data, resuscitative care events, data, and/or feedback,
CPR parameters and/or feedback, timing information, location information, defibrillation
parameters, physiological information, etc. The defibrillator 1210 may communicate
with the external computing device 1290 via a short range wireless connection (e.g.,
Bluetooth®, Wi-Fi, etc.), a cellular network and/or a computer network (e.g., an Internet
Protocol network).
[0081] Although shown as separate units in FIG. 12, in an implementation, the automated
chest compression device 1220 may include some or all of the defibrillator electronics.
A power supply for the chest compression device may provide power for compressions
as well as defibrillation. This configuration may provide a benefit of reducing the
amount of equipment that the rescuer needs to carry to the scene of a cardiac arrest.
[0082] Referring to FIGS. 13A and 13B, schematic diagrams of examples of defibrillation
assemblies are shown. During the course of resuscitation, it may be desirable for
the rescuer to apply an electrode assembly to the patient's chest. The rescuer may
utilize the electrode assembly in conjunction and coordination with various types
of chest compressions. The various types of chest compressions include, for example
but not limited to, the types of compressions listed in Table 1. The electrode assembly
may remain in place on the chest of the patient when chest compressions are delivered.
[0083] Referring to FIG. 13A, the electrode assembly 1320 includes a first electrode 1324,
a second electrode 1326, and a chest compression assembly 1328. The rescuer may place
the first electrode 1324 and the second electrode 1326 in an anterior-anterior position
or an anterior-posterior position such that a therapeutic current may travel through
the patient's heart. As an example, in operation, the rescuer may place the first
electrode 1324 above the patient's right breast and may place the second electrode
1326 below the patient's left breast. The electrode assembly 1320 further includes
a chest compression assembly 1328. The chest compression assembly 1328 includes the
motion sensor 118, as described above. The assembly 1328 may include the motion sensor
118 disposed within a plastic housing (not shown). The motion sensor 118 moves with
the assembly as the rescuer performs chest compressions and decompressions on the
patient so that the motion of the motion sensor 118 substantially matches the motion
of the patient's chest. The chest compression assembly 1328 is shown in FIG. 13A as
having an "X" printed on its top surface to indicate to the rescuer where to place
his or her hands when delivering chest compressions and decompressions to a patient.
The chest compression assembly 1328 is configured to transmit signals from the motion
sensor 118 to the defibrillator 1210 through the wired leads 1312. Although shown
as a wired connection in FIG. 13A, in an implementation, chest compression assembly
1328 may transmit signals wirelessly from the motion sensor 118 to the defibrillator
1210 and/or to another computing device (not shown), for example, a mobile device,
a portable computer, a medical device, a desktop computer, etc.
[0084] Referring to FIG. 13B, the electrode assembly 1330 includes a first electrode 1334,
a second electrode 1336, and a chest compression assembly 1338. The first electrode
1334 may be a single electrode, as similarly described above with regard to the first
electrode 1324. The second electrode 1336 may include the chest compression assembly
1338. The chest compression assembly 1338 includes the motion sensor 118 and is substantially
similar to the chest compression assembly 1328 as described above. Aside from differing
in geometry and in the inclusion of the chest compression assembly 1338, the second
electrode 1336 is substantially similar to the second electrode 1326 as described
above. Similarly to the electrodes 1324 and 1326, the rescuer may place the first
electrode 1334 and the second electrode 1336 in an anterior-anterior position or an
anterior-posterior position such that a therapeutic current may travel through the
patient's heart.
[0085] As discussed above, the motion sensor 118 is disposed in (i.e., is a component of)
the electrode assemblies 1320 and 1330. However, in an implementation, defibrillation
electrode assemblies may not include the motion sensor 118 (i.e., the motion sensor
may be a component of an assembly physically separate from the electrode assembly).
For example, as described above (with regard to FIGS. 1, 2A, 2B, 3C, and 3D) the compression
puck 110, the compression belt 210, the compression pad 289, the compression target
pad 330, and/or the hand-held ACD device 310 may include the motion sensor 118. The
rescuer may use these described compression components inclusive of the motion sensor
118 in conjunction and/or coordination with defibrillation electrode assemblies. The
defibrillator may include a first connection to the motion sensor 118 and a second
connection to the defibrillation electrodes. The first connection to the motion sensor
118 may be a wired and/or wireless connection. In a further implementation, the defibrillator
and/or other computing device may receive signals from the motion sensor 118 disposed
in the electrode assembly and receive signal from the motion sensor 118 disposed in
another component or assembly.
[0086] The defibrillator 1210 is configured to connect to electrode assembly 1320 and/or
electrode assembly 1330 by way of a wired leads 1312 connected to the defibrillator
1210 by way of a plug (not shown). For example, the defibrillator 1210 may include
a female or male connection, and the plug may include a corresponding connection in
a manner that is well known in the art. The wired leads 1312 may transmit power to
and/or from the defibrillator 1210. For example, current to provide a therapeutic
shock to a patient may flow from the defibrillator to the electrode assembly 1320
and/or 1330. As another example, electrical signals for corresponding to electrocardiogram
(ECG) information, motion sensor information, and/or measurements of chest impedance
information may flow from the electrode assembly 1320 and/or 1330 to the defibrillator
1210.
[0087] The electrodes 1324, 1326, 1334, and 1336 may include a flexible foam layer that
includes a gel layer on the bottom of the electrode configured to conduct the defibrillation
shock to the patient. Before they are deployed, the various electrodes and assemblies,
as described for example herein, may be stored in a sealed packet to keep the gel
layer moist, and the wires may be coiled to reduce needed space. A rescuer may open
the packet, plug the wires into the defibrillator 1210, and if necessary, read instructions
on the back sides of the electrodes and/or the packet regarding the proper manner
to apply the electrodes (e.g., with graphics that show the peeling off of covers over
the electrode gels and also show images of the proper placement of the electrodes
on a line-drawn patient). In some instances, the wires may already be plugged into
the defibrillator 1210. For example, the wires may extend through a sealed hole out
of the sealed packet. For the electrode 1336, the gel layer may exclude (i.e., may
not extend under) the attached chest compression assembly 1338. The chest compression
assembly 1328 and/or 1338 may include an adhesive layer on a surface configured to
removably attach to the patient. This may prevent the motion sensor from moving relative
to the patient's chest and/or separating from the patient's chest during chest compressions
and decompressions. Such an adhesive layer may improve the accuracy of the chest motion
determined from the motion sensor signals.
[0088] In an implementation, one or more of the electrodes 1324, 1326, 1334, and 1336 may
include indicia (e.g., textual and/or graphical instructions) on a surface of the
electrode(s) that may indicate how to deploy the electrode(s) and/or how to place
the electrode(s) on the patient. Alternatively, or additionally, the defibrillator
1210 may display instructions and/or provide verbal instructions. The instructions
may indicate procedures for using the electrode(s) and/or the defibrillator. The electrodes
1324, 1326, 1334, and/or 1336 may be configured to sense an ECG reading from the patient
and/or to measure the chest impedance of the patient. These electrodes may transmit
signals indicative of these sensed parameters to the defibrillator 1210.
[0089] In various implementations, one or more of the chest compression assemblies 1328
and/or 1338 may include a chest compression assembly display (not shown). The chest
compression assembly display is disposed on the chest compression assembly and may
provide feedback that is directed to the rescuer who is performing the chest compressions
and decompressions. The feedback may be similar to feedback provided by the display
168 and may include chest compression information, rescuer positioning information,
and/or other resuscitative care feedback. One or more of the chest compression assemblies
1328 and/or 1338 may further be configured to provide audio feedback and/or haptic
feedback. The defibrillator 1210 may determine the feedback and control the chest
compression assembly display. In an implementation, the chest compression assembly
may include a processor and a memory and may determine the feedback and control the
chest compression assembly display. In an implementation, the chest compression assembly
may determine, store, receive, and/or transmit information to/from the defibrillator
1210 and/or another computing device. The information may include patient medical
data, resuscitative care data, CPR parameters, timing information, location information,
etc.
[0090] In an implementation, the electrode assembly 1320 and/or 1330 may include one or
more LEDs. The LEDs may provide feedback for the rescuer. For example, the LEDs may
blink, remain illuminated and/or change color to indicate a chest compression rate,
depth, and/or release velocity, a rescuer position switch, a defibrillation timing,
and/or other resuscitative care feedback.
[0091] The electrode assembly 1320 and electrode assembly 1330 are examples only and not
limiting of the disclosure. Other electrode assembly configurations are compatible
with the systems and methods described herein.
[0092] Referring to FIG. 14, a schematic diagram of an example of a defibrillator configured
to provide real-time rescuer feedback is shown. The features shown in FIG. 14 are
examples only, and not limiting of the disclosure, of information that can be displayed
to the rescuer. A display portion 1402 of the defibrillator 1210 may provide information
about patient status and CPR administration quality during the use of the defibrillator
device. As shown on display 1402, during the administration of chest compressions
and decompressions, the defibrillator 1210 may display information about the chest
compressions and decompressions, for example, the information displayed in box 1414.
As illustrative examples, a filtered ECG waveform 1410 and a CO2 waveform 1412 are
shown. Alternatively, or additionally, the defibrillator 1210 may display an SpO
2 waveform.
[0093] During chest compressions and decompressions, the defibrillator processor 1262 may
generate the filtered ECG waveform by gathering ECG data points and motion sensor
readings and filtering motion-induced (e.g., CPR-induced) noise out of the ECG waveform.
The filtered ECG waveform may reduce interruptions in CPR as compared to a non-filtered
ECG waveform. The non-filtered ECG waveform may include artifacts from chest compressions
and decompressions that may make it difficult for the rescuer to discern the presence
of an organized heart rhythm unless compressions and decompressions are halted. Filtering
out these artifacts may allow rescuers to accurately view the heart rhythm without
stopping chest compressions and decompressions.
[0094] The defibrillator processor 1262 may control the display to provide CPR parameters
in box 1414 automatically in response to detecting chest compressions. For example,
the CPR parameters may include the chest compression rate 1418 (e.g., number of compression
cycles per minute) and the chest compression depth 1416 (e.g., depth of compressions
in inches or millimeters). Displaying the measured rate and depth data, in addition
to, or instead of, an indication of whether the values are within or outside of an
acceptable range may enhance the value of the feedback for the rescuer. For example,
if an acceptable range for chest compression depth is 25 to 60 mm, providing the rescuer
with an indication that his/her compressions and decompressions are only 15 mm may
allow the rescuer to determine how to correctly modify his/her administration of the
chest compressions and decompressions (e.g., he or she can know how much to increase
effort, and not merely that effort should be increased some unknown amount).
[0095] The defibrillator processor 1262 may also control the display provide a perfusion
performance indicator (PPI) 1420. The PPI 1420 maybe a geometric shape (e.g., a diamond,
square, a rectangle, a circle, a triangle, or other polygon) with an amount of fill
that is in the shape differing over time to provide feedback about one or more of
the rate and depth of the chest compressions. When the rescuer performs manual CPR
adequately (e.g., according to ACLS guidelines and/or at a rate of about 100 compressions
and decompressions per minute (CPM) with the depth of each compression greater than
40 mm) the fill will cover the entire area of the geometric shape. For example, the
entire indicator will be filled. As the rate and/or depth decreases below acceptable
limits, the fraction of the filled area of the geometric shape decreases. The PPI
1420 may provide a visual indication of the quality of the CPR. Further, the PPI 1420
may provide a target for the rescuer to keep the PPI 1420 completely filled.
[0096] As an example of a defibrillator display layout, the filtered ECG waveform 1410 may
be a full-length waveform that may fill the entire span of the display device, while
the second waveform (e.g., the CO2 waveform 1412) may be a partial-length waveform
that fills only a portion of the display. A portion of the display beside the second
waveform provides the CPR information in box 1414. For example, the display may split
the horizontal area for the second waveform in half, displaying waveform 1412 on left,
and CPR information on the right in box 1414. However, the layout, configuration,
and included information for the display 1402 as described above are examples only
and other layouts, configurations, and included information are within the scope of
the disclosure.
[0097] As another feedback example, a reminder 1421 regarding "release" in performing chest
compression is shown in FIG. 14. Specifically, a fatigued rescuer may lean forward
on the chest of a patient and not sufficiently release pressure on the sternum of
the patient at the top of each decompression stroke. This may reduce the perfusion
and circulation accomplished by the chest compressions. The defibrillator processor
1262 may control the display 1402 to provide the reminder 1421 when the defibrillator
processor 1262 determines that the rescuer is not sufficiently releasing. For example,
signals from the motion sensor 118 may exhibit an "end" to the compression cycle that
is flat and thus indicates that the rescuer is maintaining pressure on the sternum
to an unnecessary degree.
[0098] The defibrillator processor 1262 may control the display to change the data provided
to the rescuer based on the actions of the rescuer and/or based on the identified
type of chest compressions. For example, the defibrillator processor 1262 may selectively
provide or withhold displayed feedback (e.g., the defibrillator processor 1262 may
withhold and/or modify the displayed feedback) as described above based on the identified
type of chest compressions. A display area designated for withheld feedback (e.g.,
the box 1414 which is designated for depth and rate feedback) may be dark or otherwise
non-illuminated and/or absent of displayed information.
[0099] The defibrillator 1210 may provide spoken and/or tonal audible feedback and/or haptic
feedback as an alternative or in addition to the examples of visual indications described
above. As an example, the defibrillator 1210 may emit a sound through speaker 1422
in the form of a metronome to guide the rescuer in the proper rate of applying CPR
compressions. The defibrillator may not provide the audible and/or haptic feedback
based on the identified type of CPR compressions. For example, the defibrillator may
silence the metronome and/or other audible feedback.
OTHER CONSIDERATIONS:
[0100] The features described can be implemented in digital electronic circuitry, or in
computer hardware, firmware, software, or in combinations of them. The apparatus can
be implemented in a computer program product tangibly embodied in an information carrier,
e.g., in a machine-readable storage device for execution by a programmable processor;
and method steps can be performed by a programmable processor executing a program
of instructions to perform functions of the described implementations by operating
on input data and generating output. The described features can be implemented advantageously
in one or more computer programs that are executable on a programmable system including
at least one programmable processor coupled to receive data and instructions from,
and to transmit data and instructions to, a data storage system, at least one input
device, and at least one output device.
[0101] A computer program is a set of instructions that can be used, directly or indirectly,
in a computer to perform some activity or bring about some result. A computer program
can be written in any form of programming language, including compiled or interpreted
languages, and it can be deployed in any form, including as a stand-alone program
or as a module, component, subroutine, or other unit suitable for use in a computing
environment. Storage devices suitable for tangibly embodying computer program instructions
and data include all forms of non-volatile memory, including by way of example semiconductor
memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks such
as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and
DVD-ROM disks.
[0102] The computing device 160 described herein may include, or be operatively coupled
to communicate with, one or more mass storage devices for storing data files; such
devices include magnetic disks, such as internal hard disks and removable disks; magneto-optical
disks; and optical disks.
[0103] The terms "machine-readable medium," "computer-readable medium," and "processor-readable
medium" as used herein, refer to any medium that participates in providing data that
causes a machine to operate in a specific fashion. Using a computer system, various
processor-readable media (e.g., a computer program product) might be involved in providing
instructions/code to processor(s) for execution and/or might be used to store and/or
carry such instructions/code (e.g., as signals).
[0104] In many implementations, a processor-readable medium is a physical and/or tangible
storage medium. Such a medium may take many forms, including but not limited to, non-volatile
media and volatile media. Non-volatile media include, for example, optical and/or
magnetic disks. Volatile media include, without limitation, dynamic memory.
[0105] Common forms of physical and/or tangible processor-readable media include, for example,
a floppy disk, a flexible disk, hard disk, magnetic tape, or any other magnetic medium,
a CD-ROM, any other optical medium, punch cards, paper tape, any other physical medium
with patterns of holes, a RAM, a PROM, EPROM, a FLASH-EPROM, any other memory chip
or cartridge, a carrier wave as described hereinafter, or any other medium from which
a computer can read instructions and/or code.
[0106] Various forms of processor-readable media may be involved in carrying one or more
sequences of one or more instructions to one or more processors for execution. Merely
by way of example, the instructions may initially be carried on a flash device, a
device including persistent memory, and/or a magnetic disk and/or optical disc of
a remote computer. A remote computer might load the instructions into its dynamic
memory and send the instructions as signals over a transmission medium to be received
and/or executed by a computer system.
[0107] The computing device 160 may be part of a computer system that includes a back-end
component, such as a data server, or that includes a middleware component, such as
an application server or an Internet server, or that includes a front-end component,
such as a client computer having a graphical user interface or an Internet browser,
or any combination of them. The components of the system can be connected by any form
or medium of digital data communication such as a communication network. Examples
of communication networks include a local area network ("LAN"), a wide area network
("WAN"), peer-to-peer networks (having ad-hoc or static members), grid computing infrastructures,
and the Internet. The computer system can include clients and servers. A client and
server are generally remote from each other and typically interact through a network,
such as the described one. The relationship of client and server arises by virtue
of computer programs running on the respective computers and having a client-server
relationship to each other.
[0108] Substantial variations may be made in accordance with specific requirements. For
example, customized hardware might also be used, and/or particular elements might
be implemented in hardware, software (including portable software, such as applets,
etc.), or both. Further, connection to other computing devices such as network input/output
devices may be employed.
[0109] Information and signals may be represented using any of a variety of different technologies
and techniques. For example, data, instructions, commands, information, signals, and
symbols that may be referenced throughout the above description may be represented
by voltages, currents, electromagnetic waves, magnetic fields or particles, optical
fields or particles, or any combination thereof.
[0110] The methods, systems, and devices discussed above are examples. Various alternative
configurations may omit, substitute, or add various procedures or components as appropriate.
Configurations may be described as a process which is depicted as a flow diagram or
block diagram. Although each may describe the operations as a sequential process,
many of the operations can be performed in parallel or concurrently. In addition,
the order of the operations may be rearranged. A process may have additional stages
not included in the figure. Specific details are given in the description to provide
a thorough understanding of example configurations (including implementations). However,
configurations may be practiced without these specific details. For example, well-known
circuits, processes, algorithms, structures, and techniques have been shown without
unnecessary detail in order to avoid obscuring the configurations. This description
provides example configurations only, and does not limit the scope, applicability,
or configurations of the claims. Rather, the preceding description of the configurations
will provide those skilled in the art with an enabling description for implementing
described techniques. Various changes may be made in the function and arrangement
of elements without departing from the scope of the disclosure.
[0111] Also, configurations may be described as a process which is depicted as a flow diagram
or block diagram. Although each may describe the operations as a sequential process,
many of the operations can be performed in parallel or concurrently. In addition,
the order of the operations may be rearranged. A process may have additional stages
or functions not included in the figure. Furthermore, examples of the methods may
be implemented by hardware, software, firmware, middleware, microcode, hardware description
languages, or any combination thereof. When implemented in software, firmware, middleware,
or microcode, the program code or code segments to perform the tasks may be stored
in a non-transitory processor-readable medium such as a storage medium. Processors
may perform the described tasks.
[0112] Components, functional or otherwise, shown in the figures and/or discussed herein
as being connected or communicating with each other are communicatively coupled. That
is, they may be directly or indirectly connected to enable communication between them.
[0113] As used herein, including in the claims, "and" as used in a list of items prefaced
by "at least one of' indicates a disjunctive list such that, for example, a list of
"at least one of A, B, and C" means A or B or C or AB or AC or BC or ABC (i.e., A
and B and C), or combinations with more than one feature (e.g., AA, AAB, ABBC, etc.).
As used herein, including in the claims, unless otherwise stated, a statement that
a function or operation is "based on" an item or condition means that the function
or operation is based on the stated item or condition and may be based on one or more
items and/or conditions in addition to the stated item or condition.
[0114] Having described several example configurations, various modifications, alternative
constructions, and equivalents may be used without departing from the disclosure.
For example, the above elements may be components of a larger system, wherein other
rules may take precedence over or otherwise modify the application of the invention.
Also, a number of operations may be undertaken before, during, or after the above
elements are considered. Also, technology evolves and, thus, many of the elements
are examples and do not bound the scope of the disclosure or claims. Accordingly,
the above description does not bound the scope of the claims.
[0115] Due to the nature of software, functions described above can be implemented using
software, hardware, firmware, hardwiring, or combinations of any of these. Features
implementing functions may also be physically located at various locations, including
being distributed such that portions of functions are implemented at different physical
locations.